Firing mechanism



Oct. 10, 1950 J. w. CHANNELL FIRING MECHANISM 2 Sheets-Sheet 1 Filed March 15, 1943 INVENTOR Jami; Wcha/miz 7M ATTORNE I Oct. 10, 1950 J. w. CHANNELL FIRING MECHANISM 2 Sheets-Sheet 2 Filed March 15, 1943 INVENTOR may WCfiO/Z/Zll ATTORNEY Patented Oct. 10, 1950 2,525,477 FIRING MECHANISM James W. Channell,,.San Marino, Calif., assignor to the United States of America as represented by the Secretary f;the Navy,

Application March 15, 1943, Serial N 479,271

This invention relates to firing mechanisms, and more particularly to impact firing mechanisms for bombs.

It is an object of this invention to provide a firing mechanism for a bomb wherein the booster charge and the detonator are resiliently held apart, and wherein the booster is moved against the resilient means upon impact of the bomb to receive the detonator in a recess therein provided.

A further object of the invention is to provide in a firing mechanism of the character described, latching means to hold the booster in its forward position after impact of the bomb.

Another object of the invention is to provide a firing mechanism of the character described with a mercury switch in which the contacts of the switch are in one chamber and the mercury in a separate chamber, with means to transfer the mercury from the one chamber to the contact chamber by the movement of the booster upon impact of the bomb.

Still another object of this invention is to provide a firing mechanism of the character described with means for a time delay between the impact of the bomb and the firing thereof.

Yet further object of this invention is to provide a firing mechanism of the character described with a battery cell normally inactive, but adapted to be activated upon impact of the, bomb.

Yet another object of this invention is to provide a firing mechanism of the character with a safety release to prevent accidental movement of the booster.

Still another object of this invention is to provide a highly improved, compact and rugged firing mechanism of the character described which shall be relatively inexpensive to manufacture, extremely safe in handling, yet positive and efiicient to a high degree in use.

Other objects of this invention will in part be obvious and in part hereinafter pointed out.

This invention accordingly consists in the features of construction, combinations of elements, and arrangements of parts which shall be exem plified in the construction hereinafter described, and of which the scope of application will be indicated in the following claims.

In the accompanying drawings in which several embodiments of this invention are illustrated:

Fig. 1 is a cross sectional view of a firing mechanism embodying one form of the invention.

Fig. 2 is a cross sectional view of a modified form of mercury switch.

Fig. 3 is a cross sectional view taken along t line 33 of Fig. 2.

12 Claims. (01. 10.2-70.2)

Fig. 4 review of the nose cap switch and battery section, partly in' elevation and partly in cross section.- 7 H Fig.,5 is a plan view of the nose cap switch.

Fig. 6 is a schematicwiring diagram of one form of the firing circuit.

Fig. 7 is a view of the battery section, partly in elevation and partly in cross section.

Fig. 8 is anelevational view of the firing mechanism positioned in a projectile.

Fig. '9 isa, schematic wiring diagram of a sec shell or casing l6 threaded to the nose cap or striking point I]. Fitted within the nose portion of shell 16 is a battery section l8 consisting of a threaded tube i9 and a. dry cell 20. A washer 2| of insulating material is placed between the battery and nose cap I1. l

Threaded to the tube I9 is a mercury switch section 22, comprising a member 23 made of insulating material. Member 23 is formed with two cylindrical recesses 24, hereinafter called the immediate chambers, sealed by screws 25. Each recess is provided with a pair of spaced contacts 25 V (Fig. 6). Member 23 is further formed with a third cylindrical recess 21, filled with mercury 21a, and hereinafter called the reservoir. A plug 28 is threaded into the reservoir. Interconnecting the reservoir and the two immediate chambers 24, are two passageways 29, each passageway be:

ingprovided'with a small spring valve 3!] (Fig. 2).

Means is provided to pumpthe mercury from the. reservoir through the passagew'ays into the two immediate chambers. v I

To this endQthere is prdvided a plunger 3|, one endof which passes through the plug 28 intothe reservoir.- -Fixed to the end of the plunger by means of a nut 32 and steel washer 33, is a leather washer' 34. Plunge-rfil. is slidably received within a tubular mernbe1g35 threaded tothe member 23.

A light coil spring36;about plunger 3| tends to hold the plunger against movement inv the forward direction. A; second coil spring 31 abuts a nut 38 threaded to the end of the plunger and the forward portion of anexternal plunger 39 slidably received within tubular member 35. The external plunger 39 is provided with a large collar 49 fixed to its end and adapted to hold a detonator 4 I Forward motion of the plunger 3| will pump the mercury through the passageways 29 into the immediate chambers. The spring valves 30 will open (11.16.1130 the increased pressureicreated' by the plunger.

In the rear portion of supporting shell I5 is a booster 4 2 comprising two concentric tubular members 43 and 44, and provided with end plates 45, formed with openings for the tubular member 43. The space between thetwo tubular members is filled with an explosive charge 46. Booster 4-2 is adapted to slide forward within shell l6, against the action of a coil spring 41,:uponimpactof the projectile, to place the detonator within the recess formed by the tubular member 4-3. Safety release l4, abutting end plate 48 of shell l6, normally 5 holds the booster .against any forward movement.

Means is provided to hold booster-42 in' its forward position after impactof the projectile.

To this end there are :provided two spring latches 49 fixed to the external surface of tube 16, the latches passing throughthe tube to rest against the surface of'tubu'lar member 44. The latches will catch behind end platewhen booster 42 moves into its 'forwar'd-position.

In operation, the projectile "is dropped after pulling out the safety release cable 44 .to-permit the potential forward movement of .booster 42. Upon impact of the'projectile'l2 with its target, booster 42will slideforward, due to its inertia, in supporting shell 16, against the action of spring 47. The detonator 4l passes within tubular member 43 of the'booster. The forward end plate 45 will abut the-collar 48, to move the external plunger 39 forward. The forward mo" tion of the external plunger will compress spring 31. 'The latches 49 will hold the booster 42 in its forward position.

Compressed spring 31 will move the plunger 3| forward against the action of the weaker spring 36, to pump the mercury from the reservoir 27 into the immediate chambers 24, opening the valves 30 in the passageways '29. The contacts of the immediate chambers will thus be bridged by the mercury to complete the firing circuit as shown in Fig. 6, to fire the detonator. The detonator in turn will set ofi the explosive charge 48 of the booster which in turn will explode the charge of the projectile.

It is evident from the above description and from the wiring diagram as shown by Fig. 6, that the firing mechanism could be constructed with only one immediate chamber 24, instead of the two as disclosed. By using two immediate chambers and placing the contacts in each side of the line of the detonator, addedsafety is obtained in the handling of the projectile. The use of only one immediate chamber-would necessitate connecting one side of the detonator directly to the battery cell. The possibility of the battery cell grounding against thesupporting shell and completing the firing circuit for the detonator is thus avoided.

Referring to Fig. 7'of the drawings, a different type of battery cell is disclosed to energize the firing circuit of the detonator 4|.

Fitted into the nose portion of supporting shell [6 is a, shell 50 to which member '23 is threaded. Fixed within shell 50 is a recessed member 5!. Fitted within the recess of member 5! is a casing r washer 58.

52 of insulating material. Within casing 52 is a battery cell 53, normally inactive, enclosed in a glass envelope 54. Enclosing the envelope 54 and its battery cell is a second glass envelope 55 filled with an activating fluid, not shown, for the battery cell. Both glass envelopes are formed with pointed ends which pass through the casing 52.

Means is now provided to break .the pointed ends of both glass envelopes to permit the activating fluid to come in contact with the battery cell.

To this end shell I6 is now provided with a nose cap 56 having a removable safety pin 5?. The internal end. of safety. pin supports a heavy metal The pointed ends of the glass envelopes are received within the washer. Before use, the safety pin 51 is withdrawn, leaving the washer supported by the tips of the glass envelopes. Upon impact of the projectile, this washer will slide sideways breaking the ends of the glass envelopes to bring the activatingfiuid in contact withithe battery cell.

Referring to Figs. 2, 3, 4, 5 and--9in which a second embodiment of the present invention is disclosed, means is provided-to delay-.the'firing of the detonator afteriirnpact of"the-:projecti-lc.

The switch section -'.Z2-isnow provided withtwo immediate ChambelS"Z4,;a reservoir 21-filledwith mercury, and 'a fourth recess 16, hereinafter called the delaychamber. -The delay'chamber is provided with-a pair'ofispaced contacts fi l. vInterconnecting the delay chamber and. one .:of.;the immediate chambers is a passageway- 62 :ior the mercury (Fig. 9).

Shell |G:is provided with aznose'capfifi having an indexing pin-64. The indexingpin 'actuates the switch :memberr65, the schematic drawing of which is showninFig:;-9.

In operation, thejndexingc pin-i is first setto'the type of firing desired. rIf 'contact firing-isdesired, the pin is set on C of the=nose cap fi3. The firing of atheide'tonatorand booster willbe the same as hereinabove described.

Should delay firing: of the detonator be desired, the indexing pinis set.onD' of the nose cap. Upon impact of the projectile, the booster will move forward tocharge the plunger spring :31. The mercury is then pumped into the immediate chambers 24 of the switch-section. Due to the setting of switch member 65 (Fig. 9), the detonator will not be fired. The mercury, after filling the immediate chambers, will flow through the passageway 62 to run into the delay chamber 60. When the contacts SI of the delay chamber are bridged by the mercury, the firing circuit for the detonator 4| is completed (Fig. 9) to set off the projectile.

The time delay in setting err the projectile may be varied according to needfby proper design of the size of theimmediate chambers, the diameter and length of the passageway interconnecting the immediate chamber and the delay-chamber and by properly positioning the contacts within the delay chamber with respect to the interconnecting passageway and/or the bottom of the delay chamber.

It will thus be seen that there is provided a device in which the several objects of this-invention are achieved and which is well adapted'tomeet the conditions of practical use.

As various possible embodiments might be made of the above inventionand as various changes might be made in the embodiments above-set forth, it is to be understood-that all'matterherein set forth, or shown in the accompanying drawings, is to be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, I claim as new and desire to secure by Letters Patent:

1. In a bomb firing mechanism, a shell adapted to be embedded in a bomb enclosing a switching device and an explosive device, resilient means normally holding said devices apart, the said explosive device being slidable forward by the force of its momentum upon impact of the bomb into position to operate said switching device, said switching device comprising a block of insulating material, two pair of spaced contacts in two normally empty chambers in said block, a quantity of mercury adjoining said chambers, a passageway leading from the mercury to said chambers and spring pressed valves normally closing said passageways, means engaging the mercury. and movable under the control of said explosive device as it moves forward to cause the mercury to force said valves open and to flow through said passageways to bridge said contacts, and an energizing circuit for firing said explosive device controlled by said switching device.

2. In a bomb firing mechanism, a shell adapted Y. I

to be embedded in a bomb enclosing a switching device and an explosive device, resilient means normally holding said devices apart, one of said devices being slidable towards the other by the force of its momentum upon impact of the bomb into position to cause the actuation of said switching device, said switching device comprising a block of insulating material having three chambers with a passageway there between together with stoppers normally closing said passageways, two of said chambers being provided with two pair of spaced contacts and the other of said chambers enclosing a conducting fluid, a plunger engaging said fluid and extending through said block into position to be engaged by said explosive device upon impact of the bomb whereby said fluid is caused to displace said stoppers and to flow through said passageways to bridge said contacts, and an energizing circuit for firing said explosive device closed by the bridging of said contacts.

3. In a bomb firing mechanism, a shell adapted to be embedded in a bomb enclosing a switching device and an explosive device, resilient means normally holding said devices apart, one of said devices being slidable towards the other by the force of its momentum upon impact of the bomb into position to cause the actuation of said switching device, said switching device comprising a block of insulating material having four chambers, the first of which encloses a conducting fluid, the second and third of which encloses two pair of spaced contacts and are connected with said first chamber by a normally closed passageway and the fourth of which encloses a pair of spaced contacts and is connected with said third chamber by an open passageway, displaceable valve means initially closing the first mentioned passageway, a plunger extending from within said first chamber through a wall of said block to a position at which the plunger may be pushed inwardly by said eXplosiVe device upon impact of the bomb to force the said fluid from said first chamber into said second and third chambers and from said third chamber into said fourth chamber, and an energizing circuit including said pairs of contacts for firing said explosive device.

4. Contact firing mechanism comprising a casing, an insulating block, a plunger, a detonator and a booster aligned in serial order in said casing, said block having three chambers with mutually connecting-passageway therebetween, "twooi said-chambers having two pairs of spaced contacts and the third enclosing aconducting fluid, saidplunger extending rearwardly from within the third chamber, resilient means to hold said booster normally apart-from said detonator while permitting forward displacement thereof bythe force of inertia into a position to b fired by said detonator, latching means to holdsaid booster against counter -,movement, resilient means to hold said detonator apart fromsaid plunger while permitting forward movement thereof towards said plunger when said detonator is engaged by said booster and said booster is approaching'its fully displaced position, resilient meansto prevent said-' plunger from normally exerting pressure on said conducting fluid while permitting forward movement of the plunger upon reactive expansion of the resilient detonator holding means to cause said conducting fluid to flow'through said passageways to bridge said contacts, and an energizing circuit for firing said detonator including said contacts;

- 5. Abomb firing mechanismaccording to claim 3, provided with ai switch to exclude at will one o'f said pairs of contacts from said energizing circuit.- r

6.-' Electrical activating means for bomb firing mechanism comprising a two-compartment frangible container, each of thecompartments being tipped and thereby sealed, one of the tips extending inside of the other tip, an initially inert cell in one compartment, an activating fluid for the cell in the other compartment, and means for shearing the compartment'tips thus to break the seal between the compartments.

'7. Electrical activating means for bomb firing mechanism frangible container, said compartments having telescoped sealing tips, an initially inert cell in one compartment, an activating fluid for the cell in the other compartment, and a weight movable transversely of the container to shear both tips and thus break the seal between the compartments.

8. Electrical activating means for bomb firing mechanism comprising a two-compartment frangible container, said compartments having telescoped sealing tips, an initially inert cell in for extruding the fluid to bridge the contacts,

a detonator carried by the other part of the plunger, said detonator being connected across the circuit, and a booster spaced from the detolnator, being movable into proximity therewith and then progressively to close and displace the two-part plunger. I V

10. Firing mechanism comprisin a casing, 'an electrical circuit embodied in the casing, including a source of current and at least one pair of contacts, a reservoir containing a volume of conducting fluid, said reservoir having a passageway communicating with the contacts, a twopart plunger of which one part is spaced from comprising a two-compartment :the otherzpart andfis displaceable in the reservoir for extruding the fluid to bridge the con- .tacts,;a detonator, abuttable means by which the .detonatoris attached to the other part of the plunger, said detonator being connected across the circuit, and a booster spaced from the detonator, being movable into abutment with the abuttable means, thereupon to progressively close :anddisplace the two-part plunger.

11. Firing mechanism for bombs and the ,like, comprising fluid contact-making means, an electrical circuit having terminals bridgeable by displacement of and contact with said fluid means, a booster spaced from the contact-making means but movable toward it, a twowpart :plunger of which one part is spaced from the other part and is adapted to pump the ,fluid means, a detonator'carried by the other plunger 'part which is engageable by the booster, g-said detonator being connected across the circuit,-and .tension means exercising dilTerent degrees of tension on the respective parts of the two-part plunger, therefore'enablin the plunger ;-parts to yield progressively after said other plungerpart is picked up duringthe movement;of'thebooster.

12. Contact firing mechanism comprising a casing, a battery, a switch for a firing circuitrembracing the battery, said switch including open contacts, an entrapped 'volume of contactbridging fluid and a plunger toextrude'it from its entrapment, a detonator and a booster movable from an unarmed position by the force of f8 inertia into, an armed position to be fired by said detonator, and a two-part two-tension resilient means coupling the plunger to said detonator, said resilient means yielding between the resistance to extrusion of the fluid and the impelling inertia movement of the detonator towards said switch when the detonator is engaged by said booster, the heavier-tensioned part of the last mentioned resilient means being of sufiicient strength by reactive expansion after compression to fully drive said plunger and causethe operation of said switch by the extruded fluid then .bridging the contacts. JAMES W. CHANNEIL.

REFERENCES CITED The following references are of record in-the file of this patent:

UNITED STATES PATENTS Number Name Date 935,188 Cartwright Sept. 28, 1909 1,052,606 Maxim Feb. 11, 1913 1,374,705 Wright Apr. 12, 1921 1,545,139 Greenwell July 7, 1925 FOREIGN PATENTS Number Country Date 20,620 France June '4, 1918 336,844 Great Britain Oct. 23,1930 347,134 Italy Mar. 18, 1937 

